1. Field of the Invention
The present invention generally relates to a system for administrating network elements, and in particular to an system and method for managing network nodes or workstations which are organized in a hierarchical structure.
2. Description of the Related Art
In networking and telecommunications, it is well known that an OSI (Open Systems Interconnection) provides a seven-layer model as well known. Since an open system in the OSI is a computer that supports the model for connecting systems on a network and communicating among these computers, the OSI is used to easily construct a heterogeneous network, which results in an increasing number of network elements, especially, in a nationwide network. In cases where a wide area network includes a large number of network elements which are separated by distances on a nationwide scale, a hierarchical management strategy is preferably employed to efficiently administrate such a wide area network.
In the hierarchical management, a single management workstation manages the network hosts or nodes, terminals and cables (hereinafter referred to as "objects") in various layers which are hierarchically organized into a tree structure for network management. More specifically, as shown in FIG. 1, the tree consists of a topmost (or root) object (A) and child objects that are directly below the topmost object (A). A child object itself is a tree, and can have child objects of its own. In other words, a child object is included in a parent object in all layers. Such a tree, as shown in FIG. 1, is stored in a tree table provided in the management workstation.
A reception module which is a process generated in the management workstation is capable of controlling each of the objects such that the various settings of an object (e.g. a host computer) are read out or changed and further the object is deleted or another object is attached on the network. In the case of deletion of an object on the network, the reception module cannot delete the object in question without confirming that all the child objects of the object are inactive. In order to do such a confirmation, the management workstation is provided with an active state table which contains active object names as well as the numbers of active operations corresponding to the respective active object names. The deletion of an object can be performed only when the object in question and its child objects have no active operations, that is, the number of active operations is zero.
Referring to FIG. 2, when a network administrator requests the deletion of an object, the management workstation generates a sending module which is a request sending process and the reception module receives the deletion request from the sending module (steps S101 and S102). Upon reception of the deletion request, the reception module retrieves the object and its child objects from the tree table and then checks whether the retrieved objects include an active object with referring to the active state table (step S104). If at least one active object is included in the retrieved objects, an error message that the deletion is impossible is sent back to the sending module, and otherwise the object and its child objects are deleted (steps S105-S107).
In this manner, taking the tree structure as shown in FIG. 1 as an example, the node (B) requested to be deleted and its child nodes (C)-(G) are deleted from the network by the network administration workstation.
However, in the conventional method, the network administrator receives only the error message when an active object is included in the tree of the object requested to be deleted. Therefore, the network administrator has to retry the same deletion request after a lapse of an appropriate time interval. In addition, the sending module has to check whether the deletion request input from the network administrator is properly received by the control module. Therefore, the sending module is burdened with complicated tasks.